This invention relates generally to the field of electrical circuits, and more specifically to a system which supplements existing safety devices by real-time monitoring of current and voltage levels in light circuits to actuate a safety disconnect.
Electrocution deaths due to failures in large-scale lighting systems are an increasing public safety concern. Even if a lighting system was properly designed, an aging electrical infrastructure, unplanned wiring degradation due to saltwater intrusion, hurricane, tornados, flooding, storm damage, or human intervention (e.g. car accidents) can cause a lighting circuit to become dangerous for any person who comes in contact with the damaged circuit. This leaves the service man, as well as the private individual, in a potentially dangerous situation. For example, in the year 2000 alone three people were electrocuted in the Miami area due to accidental contact with a malfunctioning electrical circuit.
There are existing safety systems in place designed to prevent these accidents, however, such systems are not capable of addressing the unplanned circuit interrupts. In the case of street lights, for example, circuit breakers are present inside the poles themselves, and a main breaker for a street light circuit is typically located in the main service panel for the circuit. Unfortunately, not every electrical malfunction will trigger the circuit breakers. A ruptured wire in a pole may be located past a breaker in the wires, and as a result the breaker will not be tripped. A xe2x80x9csilentxe2x80x9d short circuit may be present, which creates hazardous conditions without being strong enough to enact a safety disconnect.
The most crucial factor in preventing executions is the proper grounding of each light pole. The circuit breakers only trip if the pole is grounded. With proper grounding, the pole has no electrical potential above ground. A serious problem exists that ground can be lost, and the street lighting system continues to appear to function normally because there is no ground to trip the circuit breaker. In this situation, a deadly ground fault can exist undetected in the system.
Most electrical malfunctions resulting in electrocution hazards are caused by faulty wiring, which may be ruptured or frayed, or by the installation of improperly-sized components. Since the lights may continue to function normally under these conditions, the problem may not be detected until a malfunction occurs. A common practice in street light maintenance is that poles and lines are only serviced when a light goes out or some other visible problem occurs. For reasons of public safety, it would be highly beneficial to perform an on-going diagnostic check of light circuits instead of waiting for a malfunction to take place.
There remains a great need to provide a system which can provide an added layer of safety to an existing light system. It would be obviously advantageous to detect and identify ground faults and short circuits in real time and immediately disconnect the problem light circuit. It would also be advantageous to continuously monitor the continuity of the grounding conductor of a circuit, and provide an immediate disconnect if ground is lost. These safeguards are not provided by existing safety devices.
In view of the above, it would be highly desirable to provide a computer-implemented safety system which continuously monitors the current and voltage in each circuit, as well as providing a means to continuously monitors the integrity of the grounding conductor. By monitoring the current and voltage and comparing the data with known algorithms as demonstrated in the present invention, it is also possible to detect and pinpoint problems in the circuits. The system for a light circuit safety disconnect as described herein is not shown or demonstrated in the prior art.
It is an objective of the invention to provide a safety system for light circuits which continuously monitors and analyzes the current and voltage in the circuit, and activates an emergency disconnect from the power source if hazardous conditions are detected.
It is a further objective of the invention to provide a safety system for light circuits which continuously monitors the continuity of the grounding conductor.
It is another objective of the invention to provide a safety system for light circuits which can detect short circuits which is not sufficient to blow a safety fuse.
It is still another objective of the invention to provide a safety system for light circuits which provides on-going diagnostic functions by monitoring the current and voltage in each circuit and comparing the voltage and current with known algorithms for a properly functioning light circuit.
It is yet another objective of the invention to provide a safety system for light circuits which monitors power consumption.
In accordance with the above-objectives, the present invention provides a system which supplements existing safety devices by real-time monitoring of current and voltage levels in light circuits to diagnose and pinpoint problems in the circuit, and to activate a safety disconnect in the event hazardous conditions are detected. The system includes a monitor device electrically coupled to a light circuit service panel. The monitor device includes aa switching means complementary to an existing disconnect means operable to independently disconnect a light circuit from a power source, and input means for collecting real-time data from a plurality of circuits. The input means includes a means for detecting unequal current levels in the light circuits, a means for continuous surveillance of ground wire continuity for each light circuit, and means for continuous sensing of the current and voltage levels in each light circuit. The means for sensing the current and voltage levels can be a measuring transducer. The monitor device includes a processor coupled to the input means which is operable to perform the steps of analyzing the current and voltage levels in each light circuit in real time by comparing the data with known parameters, computing power usage in each circuit and analyzing the power usage by comparison with known parameters, determining if disconnect conditions exist in each circuit; and disconnecting the circuit from a power source if hazardous conditions requiring an emergency disconnect are detected.
The means for continuous surveillance of ground wire continuity preferably comprises a plurality of ground wire test circuits corresponding to each of the plurality of light circuits, a test signal generator operable to transmit a known test signal through the ground wire test circuits, and a means for continuously sensing of the current level each of the ground wire test circuits. The processor is operable to perform the steps of analyzing said current level in each ground wire test circuit by comparing the current level with known parameters, determining if disconnect conditions exist for a light circuit, and disconnecting the light circuit from a power source if disconnect conditions exist. The disconnect conditions can be a ground fault detected by a decrease in the ground wire test circuit current level due to a discontinuity in the ground wire.
The processor is also operable to detect a short circuit or ground fault in a light circuit by comparing the current level and the voltage level with known parameters and disconnecting said light circuit if a short circuit or ground fault exists. The number of non-functional lamps on each circuit can be determined by comparing the current level and the voltage level with known parameters. The system can similarly detect non-functional components and also determine if proper size components are being used.
The system can further include a communication means coupled to the processor and a remotely located external processor, wherein the monitor device is in communication with the external processor. The monitor device transmits input data from the light circuits is transmitted to the external processor. The external processor can be in communication with a plurality of monitor devices. The communication means can be via a modem using telephonic communication methods, a radio transceiver system, or satellite communication system. The monitoring device can detect a power failure in a light circuit by comparing the current level and said voltage level with known parameters and transmitting an indication of the power failure via the communication means to the external processor or directly to the responsible utility company. The external processor can also be operable to analyze the current, voltage and power in each light circuit.